<!DOCTYPE html>
<script>
onload = () => {
    outerDiv.scrollTop = 300;
    innerDiv.scrollTop = 400;
}
</script>
<div style="height: 300px; overflow-y: scroll;" id="outerDiv">
    <div style="height: 300px;"></div>
    <div style="height: 400px; overflow-y: scroll;" id="innerDiv">
        <div style="height: 800px; width: 300px; background: green"></div>
    </div>
</div>
